The present invention relates to a connector for optical fibers and to a method for the axial positioning of the end of an optical fiber at a pre-established point in the connector.
As is known, the most common methods for connecting two optical fibers are those employing a facing connector or an expanded beam connector. In the first case, the ends of the optical fibers are directly facing one another, must be placed in end-to-end mutual contact and must be perfectly aligned. In the second case, the optical connection is carried out by means of a lens (generally spherical or cylindrical) which produces an expanded collimated beam, and the ends of the optical fibers are situated in the focus of said lens.
For both types of connectors, the problem arises of having to position and to fix permanently, with the utmost precision, the end of the optical fiber at a certain point in the connector, and more precisely, at a point on the plane of contact of the two half-connectors in the case of the facing connector and at the focus of the lens in the case of the expanded beam connector.
A first, already-known solution requires the use of a micrometric device for the advancement of the optical fiber and of very sophisticated instrumentation to define the point which ensures the "optimum" connection. The results are quite satisfactory, but the connector is rather complicated and the carrying-out of the connection very difficult.
A second already known solution suggests the cutting of the optical fiber to the desired size and then, the insertion of it into the hole of a ferrule, having substantially the same diameter as that of the optical fiber, to cause the latter to advance axially inside said hole until its end comes into contact with a movable reference surface situated at the point in which said end must be positioned, and at least securing the optical fiber in that position. A method of this type is disclosed in U.S. application Ser. No. 050,061 filed May 13, 1987, now U.S. Pat. No. 4,807,958, assigned to the assignee of the present invention. This second solution involves the risk that during the insertion of the optical fiber, the operator, because of the friction encountered, may position the end of the optical fiber at a point other than the pre-established one. Moreover, it is possible that in the hole, there can be some scraps of material and that, during the insertion, such scraps lodge on the end of the optical fiber, strongly attenuating the signal or possibly even blocking light transmission from the end of the optical fiber.